Q. What are the key values you need to configure in a multi-site failover cluster for heartbeat detection?

A. With Windows Server 2008 and above, you can configure each of the various settings related to latency of heartbeat responses and number of missed messages before a location is considered unavailable. The key values you want to tune would be:

SameSubnetDelay—Frequency heartbeats are sent. Default is one second.

SameSubnetThreshold—Missed heartbeats before an interface is considered down. Default is five heartbeats.

CrossSubnetDelay—Frequency heartbeats are sent to nodes on dissimilar subnets. Default is one second.

CrossSubnetThreshold—Missed heartbeats before an interface is considered down to nodes on dissimilar subnets. Default is five heartbeats.

You can configure these with the cluster.exe command line interface and the Set-Cluster PowerShell cmdlet.